Hydrocarbons are generally retrieved from hydrocarbon wells that are located in the subsoil. When a hydrocarbon field is located at sea, one or more holes are drilled in the topsoil from a hydrocarbon production platform in order to create a passage to retrieve the hydrocarbons to the surface. When a hydrocarbon well is depleted, or production has become economically unattractive, operations are stopped and the drilling and/or production facilities are dismantled. For a hydrocarbon production platform, dismantling amongst others includes removing all equipment from the wellbore, closing the borehole and removing any subsea equipment and pipelines. It further includes removal of the production platform. The production platform in general is connected to the hydrocarbon well, and comprises a support structure and an upper part being supported by said support structure. In practice the upper part is also often referred to as the top side of the production platform.
The known method used for removing a hydrocarbon production platform from sea comprises the following subsequent steps which will be discussed in detail;    performing well abandonment operations to abandon the well,    performing removal preparation operations on the production platform,    removing the upper part from the support structure and    removing the support structure.
The operations to abandon the well are often also referred to as “plugging and abandonment” of the well. During said operations, the borehole of the well is closed. As long as the well abandonment operations have not been completed, the well is considered to be “hot”. The moment the abandonment operations have been completed the well is considered to be “cold”.
In order to facilitate the abandonment operations, an assisting vessel is placed near the production platform for assistance during the abandonment operations. This may for instance be a jack up vessel. The assisting vessel provides the necessary equipment which is not available on the production platform. The assisting vessel furthermore may provide living quarters and a helicopter platform. The removal preparation operations on the production platform may include amongst others the checking of pipelines on the upper part to ensure there are no flammable substances left in them, checking existing or creating new lift points for removal of the upper part, securing or removing loose items, and preparatory work to facilitate the removal.
Once the removal preparation operations are completed, the upper part is removed from the support structure. This may for instance be performed by a lifting vessel, such as a crane vessel. The upper part may be transported to shore for further processing by the crane vessel, a transportation barge, a cargo vessel or the like.
After that, the support structure is removed. The support structure can include a lattice structure, also known as a jacket, or a different type of structure. Said removal of the support structure can be performed by the same or a different lifting vessel.
The well abandonment operations in general have a duration of several months, but can last up to several years. This depends on the number and type of hydrocarbon wells that needs to be abandoned, as well as other factors like the depth and distance of the well and the characteristics of the different soil formations that are crossed by the wellbore.
The removal preparation operations in general have a duration of several weeks up to several months, depending on the type of system to be dismantled.
The removal of the upper part from the support structure and the removal of the production platform in general takes about one or more weeks up to several months.
Thus the well abandonment operation in general is very time consuming. It is required that the assisting vessel is positioned near to the platform for the duration of said well abandonment operations. The costs for such an assisting vessel can be considerable, in the order of several hundreds of thousands of dollars per day, up to 500.000 dollar per day or even more.
In the known method, the actual removal of the production platform starts once the abandonment operations are completed (once the well is considered to be “cold”). In the technical field of hydrocarbon production platforms, there is a general assumption that for a safe removal of an hydrocarbon production platform it is required that the wells to which the production platform is connected are made “cold” before the actual removal of the production platform is started. An object of the invention is to provide an improved or at least an alternative method for removing a hydrocarbon production platform. The object is achieved by a method for removing a hydrocarbon production platform from sea, said production platform being connected to a hydrocarbon well, and comprising a support structure and an upper part being supported by said support structure, wherein the method comprises the steps of;    A. temporarily closing the well,    B. removing at least part of the upper part from the support structure,    C. positioning a well abandonment module on the support structure, which well abandonment module is constructed and arranged to perform well abandonment operations,    D. performing abandonment operations from the well abandonment module to abandon the well,    E. removing the well abandonment module from the support structure after the well abandonment operations are completed.